Neurobiologist Michael Meaney made headlines around the world 10 years ago with a study that showed that devoted maternal care — in rats at least — produced adults that were less susceptible to stress than their neglected counterparts.

That attentive mothers produce less-anxious offspring was not news. But concluding that the genetic coding of rat pups changed according to their rearing broke with the notion that our genetic makeup is set for life.

Even more provocative was the observation that genes controlling stress hormones in pups that had not been licked and groomed by their mothers also changed if they were transferred to a more attentive mother rat.

Since then, epigenetics — literally “above or upon genetics” — has become a hot area of scientific study as researchers try to determine how a gene’s activity is turned on or off by chemical marks attached to it.

Meaney, a clinical psychologist, and his colleagues at McGill University in Montreal recruited 500 pregnant women in 2004 to take part in a study about how poverty, depression and other stressors affected their children’s brain function. About 400 children are still in the study, and have been tested for everything from learning disabilities to food preferences along the way.

Meaney talked about his work in a telephone interview after arriving in Vancouver to speak at a public lecture on the University of British Columbia campus Saturday night, sponsored by the Peter Wall Institute and the Vancouver Institute.

Q: A decade after your rat study, is there consensus that epigenetic marks can be modified?

A: It was controversial (in 2004), but is now generally accepted. Then the big question was: Does it happen in humans? We published a paper in 2009 which showed the same region of the genome and the same epigenetic or chemical marks were associated with a history of childhood maltreatment. It was happening in our species in the same area of the brain and the same area of the genome.

Q: Does this mean humans can change much more than previously thought?

A: We’re looking at how this changes over time. Are these marks established in early childhood? If a child’s environment improves dramatically — if a child goes from a somewhat dysfunctional family to a very nurturing daycare, for instance — does this reverse these particular marks? One of the findings I’ll be talking about Saturday night is one in which we partnered with a group in the United States that identified child abuse as a source of illness in the 1970s. They went into homes of children who were at high risk of being abused. They worked with the mothers and improved the quality of mother-child interaction. We managed to obtain DNA from these children 25 years after this treatment program, and the treatment program accounted for a considerable amount of variance in epigenetic marks. Do we know how that translated into better health? No. But at least we know there was an enduring effect of the treatment program that we can see at the level of the DNA 25 years later.

Q: What is the most intriguing observation from the MAVAN (Maternal Adversity, Vulnerability and Neurodevelopment) study of mothers and children?

A: People who work with children have known for years that two children in the same environment react quite differently. We can say quite correctly that poverty predicts poor health outcomes and under-achievement at school. But there are successful people who grew up in poverty. We have to understand why some children are more affected by adversity in early life than are others. Probably the biggest factor in determining vulnerability is the genetic makeup of the child — some children are more sensitive to the environment in which they live. The big public health challenge is to take the genetic information in combination with their environmental influence and then define truly high-risk populations. A network of clinics funded by Brain Canada is looking at the possibility that these epigenetic marks may be the single best marker of the true vulnerability of the individual because they reflect both their genetic makeup as well as the quality of the environment in which they grew up.

Q: It sounds like science fiction.

A: It’s personalized medicine. It sounds futuristic, but if we’re right, my guess is it would take a $5 test. We’ve already published a study of people with PTSD (post-traumatic stress disorder) in which we were able to predict who would respond to treatment based on the epigenetic mark in the same area of the genome associated with childhood maltreatment.

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Finding the point where nurture meets nature

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